Csharp/CSharp Tutorial/Windows/Memory

Allocate and free memory

using System;
using System.Runtime.InteropServices;
class MainClass
{
  static void Main(string[] args)
  {
    UsePointers();
  }
  static unsafe public void UsePointers()
  {
    char * pMyArray = (char*)Marshal.AllocCoTaskMem(6);
    while (*pMyArray != "\0")
    {
      Console.WriteLine(*pMyArray);
      pMyArray++;
    }
    Marshal.FreeCoTaskMem((IntPtr)pMyArray);
  }
}

Allocate memory with System.Runtime.MemoryFailPoint

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.rupilerServices;
public class MainClass
{
    public static void Main()
    {
        using (System.Runtime.MemoryFailPoint gate = new System.Runtime.MemoryFailPoint(100))
        {
            // Some operation that actually uses the 100MB of memory�
            Console.WriteLine("Success for 100MB fail-point");
        }
        using (System.Runtime.MemoryFailPoint gate = new System.Runtime.MemoryFailPoint(1024*100))
        {
            // Some operation that actually uses the 100GB of memory�
            Console.WriteLine("Success for 100GB fail-point");
        }
    }
}

Create Heap and destroy Heap

using System;
using System.Runtime.InteropServices;
public sealed class MainClass
{
    [DllImport("kernel32.dll")]
    static extern IntPtr HeapCreate(uint flOptions, UIntPtr dwInitialSize,UIntPtr dwMaximumSize);
    [DllImport("kernel32.dll")]
    static extern bool HeapDestroy(IntPtr hHeap);
    public static void Main() {
        IntPtr theHeap = HeapCreate( 0, (UIntPtr) 4096, UIntPtr.Zero );
        HeapDestroy( theHeap );
        theHeap = IntPtr.Zero;
    }
}

Demonstrate stackalloc

using System; 
 
class MainClass { 
  unsafe public static void Main() { 
    int* ptrs = stackalloc int[3]; 
 
    ptrs[0] = 1; 
    ptrs[1] = 2; 
    ptrs[2] = 3; 
 
    for(int i=0; i < 3; i++) 
      Console.WriteLine(ptrs[i]); 
  } 
}

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Free Memory

using System;
using System.IO;
using System.Reflection;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;
public class MainClass
{
    public static void Main()
    {
        IntPtr ptr = Marshal.AllocHGlobal(1024);
        GC.AddMemoryPressure(1024);
        if (ptr != IntPtr.Zero) {
            Marshal.FreeHGlobal(ptr);
            ptr = IntPtr.Zero;
            GC.RemoveMemoryPressure(1024);
        }
    }
}

Free memory: Marshal.FreeHGlobal

using System;
using System.IO;
using System.Reflection;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;
public class MainClass
{
    public static void Main()
    {
        IntPtr ptr = Marshal.AllocHGlobal(1024);
        if (ptr != IntPtr.Zero){
                Marshal.FreeHGlobal(ptr);
                ptr = IntPtr.Zero;
        }
    }
}